bulbs - facebook code lab - correct answer

bulb4.java

public class Solution {
    public int bulbs(List<Integer> a) {
        if(a == null || a.size() == 0)
        return 0; 
        
        int count = 0; 
        int index = 0; 
        while(a !=null && index < a.size())
        {
            Integer previous = a.get(index); 
            
            boolean isEven = count%2 == 0; 
            boolean previousIsEven = previous.intValue()%2 ==0; 
            if((isEven && previousIsEven) ||(!isEven && !previousIsEven))
            {
                count ++;
            }
            
            index++; 
        }
        
        return count; 
    }
}